Set Appliance State:

Turn Hot Water Tap On
DHW Temperature control to MAX
WARNING! - Mains voltage is expected during test follow
TOPs P4 live testing procedure
Mains Power On

Observation:

Set DHW flow rate as per table, does the boiler produce
approximately a 40°C rise in temperature?
Note:
If the CH system is hot you will need cool the CH flow pipe to check if heat is passing to the radiators. This can be achieved by turning the gas OFF, the Hot tap ON, then running the appliance in service mode (hold eco and spanner buttons down for 5 seconds).